#include "blaswrap.h"
#include "f2c.h"

/* Subroutine */ int slaeda_(integer *n, integer *tlvls, integer *curlvl, 
	integer *curpbm, integer *prmptr, integer *perm, integer *givptr, 
	integer *givcol, real *givnum, real *q, integer *qptr, real *z__, 
	real *ztemp, integer *info)
{
/*  -- LAPACK routine (version 3.0) --   
       Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd.,   
       Courant Institute, Argonne National Lab, and Rice University   
       September 30, 1994   


    Purpose   
    =======   

    SLAEDA computes the Z vector corresponding to the merge step in the   
    CURLVLth step of the merge process with TLVLS steps for the CURPBMth   
    problem.   

    Arguments   
    =========   

    N      (input) INTEGER   
           The dimension of the symmetric tridiagonal matrix.  N >= 0.   

    TLVLS  (input) INTEGER   
           The total number of merging levels in the overall divide and   
           conquer tree.   

    CURLVL (input) INTEGER   
           The current level in the overall merge routine,   
           0 <= curlvl <= tlvls.   

    CURPBM (input) INTEGER   
           The current problem in the current level in the overall   
           merge routine (counting from upper left to lower right).   

    PRMPTR (input) INTEGER array, dimension (N lg N)   
           Contains a list of pointers which indicate where in PERM a   
           level's permutation is stored.  PRMPTR(i+1) - PRMPTR(i)   
           indicates the size of the permutation and incidentally the   
           size of the full, non-deflated problem.   

    PERM   (input) INTEGER array, dimension (N lg N)   
           Contains the permutations (from deflation and sorting) to be   
           applied to each eigenblock.   

    GIVPTR (input) INTEGER array, dimension (N lg N)   
           Contains a list of pointers which indicate where in GIVCOL a   
           level's Givens rotations are stored.  GIVPTR(i+1) - GIVPTR(i)   
           indicates the number of Givens rotations.   

    GIVCOL (input) INTEGER array, dimension (2, N lg N)   
           Each pair of numbers indicates a pair of columns to take place   
           in a Givens rotation.   

    GIVNUM (input) REAL array, dimension (2, N lg N)   
           Each number indicates the S value to be used in the   
           corresponding Givens rotation.   

    Q      (input) REAL array, dimension (N**2)   
           Contains the square eigenblocks from previous levels, the   
           starting positions for blocks are given by QPTR.   

    QPTR   (input) INTEGER array, dimension (N+2)   
           Contains a list of pointers which indicate where in Q an   
           eigenblock is stored.  SQRT( QPTR(i+1) - QPTR(i) ) indicates   
           the size of the block.   

    Z      (output) REAL array, dimension (N)   
           On output this vector contains the updating vector (the last   
           row of the first sub-eigenvector matrix and the first row of   
           the second sub-eigenvector matrix).   

    ZTEMP  (workspace) REAL array, dimension (N)   

    INFO   (output) INTEGER   
            = 0:  successful exit.   
            < 0:  if INFO = -i, the i-th argument had an illegal value.   

    Further Details   
    ===============   

    Based on contributions by   
       Jeff Rutter, Computer Science Division, University of California   
       at Berkeley, USA   

    =====================================================================   


       Test the input parameters.   

       Parameter adjustments */
    /* Table of constant values */
    static integer c__2 = 2;
    static integer c__1 = 1;
    static real c_b24 = 1.f;
    static real c_b26 = 0.f;
    
    /* System generated locals */
    integer i__1, i__2, i__3;
    /* Builtin functions */
    integer pow_ii(integer *, integer *);
    double sqrt(doublereal);
    /* Local variables */
    static integer curr;
    extern /* Subroutine */ int srot_(integer *, real *, integer *, real *, 
	    integer *, real *, real *);
    static integer bsiz1, bsiz2, psiz1, psiz2, i__, k, zptr1;
    extern /* Subroutine */ int sgemv_(char *, integer *, integer *, real *, 
	    real *, integer *, real *, integer *, real *, real *, integer *), scopy_(integer *, real *, integer *, real *, integer *), 
	    xerbla_(char *, integer *);
    static integer mid, ptr;
#define givcol_ref(a_1,a_2) givcol[(a_2)*2 + a_1]
#define givnum_ref(a_1,a_2) givnum[(a_2)*2 + a_1]


    --ztemp;
    --z__;
    --qptr;
    --q;
    givnum -= 3;
    givcol -= 3;
    --givptr;
    --perm;
    --prmptr;

    /* Function Body */
    *info = 0;

    if (*n < 0) {
	*info = -1;
    }
    if (*info != 0) {
	i__1 = -(*info);
	xerbla_("SLAEDA", &i__1);
	return 0;
    }

/*     Quick return if possible */

    if (*n == 0) {
	return 0;
    }

/*     Determine location of first number in second half. */

    mid = *n / 2 + 1;

/*     Gather last/first rows of appropriate eigenblocks into center of Z */

    ptr = 1;

/*     Determine location of lowest level subproblem in the full storage   
       scheme */

    i__1 = *curlvl - 1;
    curr = ptr + *curpbm * pow_ii(&c__2, curlvl) + pow_ii(&c__2, &i__1) - 1;

/*     Determine size of these matrices.  We add HALF to the value of   
       the SQRT in case the machine underestimates one of these square   
       roots. */

    bsiz1 = (integer) (sqrt((real) (qptr[curr + 1] - qptr[curr])) + .5f);
    bsiz2 = (integer) (sqrt((real) (qptr[curr + 2] - qptr[curr + 1])) + .5f);
    i__1 = mid - bsiz1 - 1;
    for (k = 1; k <= i__1; ++k) {
	z__[k] = 0.f;
/* L10: */
    }
    scopy_(&bsiz1, &q[qptr[curr] + bsiz1 - 1], &bsiz1, &z__[mid - bsiz1], &
	    c__1);
    scopy_(&bsiz2, &q[qptr[curr + 1]], &bsiz2, &z__[mid], &c__1);
    i__1 = *n;
    for (k = mid + bsiz2; k <= i__1; ++k) {
	z__[k] = 0.f;
/* L20: */
    }

/*     Loop thru remaining levels 1 -> CURLVL applying the Givens   
       rotations and permutation and then multiplying the center matrices   
       against the current Z. */

    ptr = pow_ii(&c__2, tlvls) + 1;
    i__1 = *curlvl - 1;
    for (k = 1; k <= i__1; ++k) {
	i__2 = *curlvl - k;
	i__3 = *curlvl - k - 1;
	curr = ptr + *curpbm * pow_ii(&c__2, &i__2) + pow_ii(&c__2, &i__3) - 
		1;
	psiz1 = prmptr[curr + 1] - prmptr[curr];
	psiz2 = prmptr[curr + 2] - prmptr[curr + 1];
	zptr1 = mid - psiz1;

/*       Apply Givens at CURR and CURR+1 */

	i__2 = givptr[curr + 1] - 1;
	for (i__ = givptr[curr]; i__ <= i__2; ++i__) {
	    srot_(&c__1, &z__[zptr1 + givcol_ref(1, i__) - 1], &c__1, &z__[
		    zptr1 + givcol_ref(2, i__) - 1], &c__1, &givnum_ref(1, 
		    i__), &givnum_ref(2, i__));
/* L30: */
	}
	i__2 = givptr[curr + 2] - 1;
	for (i__ = givptr[curr + 1]; i__ <= i__2; ++i__) {
	    srot_(&c__1, &z__[mid - 1 + givcol_ref(1, i__)], &c__1, &z__[mid 
		    - 1 + givcol_ref(2, i__)], &c__1, &givnum_ref(1, i__), &
		    givnum_ref(2, i__));
/* L40: */
	}
	psiz1 = prmptr[curr + 1] - prmptr[curr];
	psiz2 = prmptr[curr + 2] - prmptr[curr + 1];
	i__2 = psiz1 - 1;
	for (i__ = 0; i__ <= i__2; ++i__) {
	    ztemp[i__ + 1] = z__[zptr1 + perm[prmptr[curr] + i__] - 1];
/* L50: */
	}
	i__2 = psiz2 - 1;
	for (i__ = 0; i__ <= i__2; ++i__) {
	    ztemp[psiz1 + i__ + 1] = z__[mid + perm[prmptr[curr + 1] + i__] - 
		    1];
/* L60: */
	}

/*        Multiply Blocks at CURR and CURR+1   

          Determine size of these matrices.  We add HALF to the value of   
          the SQRT in case the machine underestimates one of these   
          square roots. */

	bsiz1 = (integer) (sqrt((real) (qptr[curr + 1] - qptr[curr])) + .5f);
	bsiz2 = (integer) (sqrt((real) (qptr[curr + 2] - qptr[curr + 1])) + 
		.5f);
	if (bsiz1 > 0) {
	    sgemv_("T", &bsiz1, &bsiz1, &c_b24, &q[qptr[curr]], &bsiz1, &
		    ztemp[1], &c__1, &c_b26, &z__[zptr1], &c__1);
	}
	i__2 = psiz1 - bsiz1;
	scopy_(&i__2, &ztemp[bsiz1 + 1], &c__1, &z__[zptr1 + bsiz1], &c__1);
	if (bsiz2 > 0) {
	    sgemv_("T", &bsiz2, &bsiz2, &c_b24, &q[qptr[curr + 1]], &bsiz2, &
		    ztemp[psiz1 + 1], &c__1, &c_b26, &z__[mid], &c__1);
	}
	i__2 = psiz2 - bsiz2;
	scopy_(&i__2, &ztemp[psiz1 + bsiz2 + 1], &c__1, &z__[mid + bsiz2], &
		c__1);

	i__2 = *tlvls - k;
	ptr += pow_ii(&c__2, &i__2);
/* L70: */
    }

    return 0;

/*     End of SLAEDA */

} /* slaeda_ */

#undef givnum_ref
#undef givcol_ref


